The art of injection molding includes devices that deliver differing silicone components to a mixer block where the components are mixed. The mixed components are then delivered to a molding machine.
Many of the known machines are pneumatically controlled; these machines often produce non-uniform parts because they suffer a loss of pressure when the pistons in the mixing and metering systems undergo a change in stroke direction. Even a momentary loss of pressure at the moment of stroke reversal can result in an inferior product.
Perhaps even more importantly, the machines known heretofore lack sophisticated metering means that insure that the components will always be mixed in their proper ratios. In an application where a component A is to be mixed with equal parts of a component B, the known machines work fine when all parts thereof are in perfect working order. However, if a leak develops anywhere in the system, the 1:1 ratio will be affected and the resulting product will not meet its design specifications. Even if no leaks appear in the system, other problems may crop up that result in an improper mixing of components. Moreover, the shot size may vary as well if the machine experiences any malfunction.
It has long been the conventional wisdom in the injection molding industry that the way to produce uniform, high quality product is to keep the machines in perfect working order. Thus, injection molding machines are frequently down for repairs, since even minor leaks or minor maladjustments result in unacceptable product.
Accordingly, inventors have turned their attention to the problem in predictable ways. Better, longer wearing seals have been developed to lengthen the time between maintenance procedures, for example. Monitoring devices that trigger alarms or machine shutdown when a leak has been detected have also been developed, and so on.
The art appears to be fully developed to those of ordinary skill, because about all that lies ahead appears to be still longer-wearing machine parts, better system monitors and detectors, and the like. It is indisputable that the art, taken as a whole in accordance with the requirements of law, neither teaches nor suggests how the art could be freed from the need for machines that operate substantially perfectly. If a machine could be developed that could produce uniform shot sizes and ideal component ratios even in the presence of leaking seals, imperfectly machined parts, and the like, such a machine would be truly revolutionary, completely unanticipated or suggested by the art, and entitled to the broadest protection afforded by the law.